public void testContainsAll_nullPresent() {
    initCollectionWithNullElement();
    assertTrue(collection.containsAll(MinimalCollection.of((E) null)));
  }

  public void testContainsAll_wrongType() {
    Collection<WrongType> wrong = MinimalCollection.of(WrongType.VALUE);
    try {
      assertFalse(
          "containsAll(wrongType) should return false or throw", collection.containsAll(wrong));